I write on behalf of the Open eBook Forum's (<http://www.openebook.org/>) Publication Structure Working Group, with a question about future development of the CSS table model.
The CSS constructs "display: table-header-group" and "display: table-footer-group" allow a particular table row (or group of rows) to be "blessed" as a table header/footer, presumably implying special treatment by some (if not all) UAs. For example, a UA with limited vertical space on its viewport might keep such a table row visible while the rest of the table scrolls, so that the user does not lose track of which cells belong to which columns.
Has the CSS WG considered an analogue to this property for table *columns*? (Column groups also, of course.) Extra-wide tables could then scroll horizontally while keeping one or more header/footer columns always visible in the viewport.
Since computer monitors tend to be landscape-view rather than portrait, I can see how this question has not intruded upon the CSS WG's notice. Ebook display devices, however, tend to be (or at least allow) portrait-view, and appropriate horizontal-scrolling behavior for large tables is a problem for them.
The next version of the OEB Publication Structure currently includes a property "oeb-table-role" invented by the PSWG. This property can only be used on an HTML <col> or <colgroup> element, or an element in which the display: property is set to "table-column" or "table-column-group." Its values are "none | header | footer | inherit" with the predictable semantics. (There has been some talk of changing the property name to something like "oeb-column-role," but nothing definite.)
If the CSS WG has thoughts in this direction, we'd rather rely on that than our own invention. Thus my inquiry. Many thanks in advance for any responses.
Dorothea Salo
Scribe, OEBF PSWG